Water-in-oil polyacrylamide-based microemulsions and related methods

ABSTRACT

A water-in-oil microemulsion, including a polyacrylamide, a fatty acid, a surfactant, an oil continuous phase, and an aqueous discontinuous phase in the oil continuous phase. The fatty acid includes a tall oil fatty acid, oleic acid, or a combination of a tall oil fatty acid and oleic acid. The water-in-oil microemulsion contains 6 to 48 parts by weight of the polyacrylamide, 30 to 62 parts by weight of the fatty acid, and 20 to 44 parts by weight of the surfactant per 100 parts by weight of the polyacrylamide, the fatty acid, and the surfactant combined.

CLAIM OF PRIORITY

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/091,686 filed on Apr. 21, 2011, which is acontinuation-in-part of U.S. patent application Ser. No. 12/0487,710filed Jun. 19, 2009, the complete disclosures of which are incorporatedherein by reference. This application is also related to U.S. patentapplication Ser. No. 14/036,214.

TECHNICAL FIELD

The present invention relates to polyacrylamide-based compositions, andmore particularly, to polyacrylamide-based compositions asmicroemulsions.

BACKGROUND

Water-soluble polymers are long known to be very useful in bothagricultural and industrial applications. Water-soluble linearpolyacrylamides, for example, are useful because of their superiorproperties of high solubility and low use rates, among others. By far,the major use for linear polyacrylamides is in the treatment of water,especially wastewater.

In wastewater treatment and uses like canal sealing, polyacrylamidecauses flocculation or agglomeration of fine particles. Flocculation,where relatively light particles are attracted together to form heavierparticles, causes the particles to sink rather than float, clarifyingthe water. In agricultural sprays, the ability of these polymers toattract and retain water and add viscosity is utilized to enhance theeffectiveness of the sprays, in addition to other purposes.

These linear polyacrylamides are commonly available in three commercialforms. First, as a water-dispersible solid, polyacrylamides may be usedin applications such as hydroseeding and canal sealing. This form slowlydissolves in water, but has a tendency to agglomerate when added tooquickly or all-at-once to water. When this happens, the lumps that areformed take hours, days or even weeks to dissolve in water. This slowdissolution property is advantageous in some applications, but is ahighly undesirable trait in situations that require quick dispersion ofthe polymer.

Second, water-dispersed polymers are used that have the distinctadvantage of already being dissolved. Examples of water-dispersedpolymers may be found in agricultural spray deposition aids, amongothers. However, not much polymer can be dissolved in water—only abouttwo percent (2%), before the solution becomes too viscous to be handledeasily.

Traditionally, the third historical form is a water-in-oil (W/O)emulsion. This involves utilizing a polyacrylamide where thepolyacrylamide chains are contained in small droplets of water that aredispersed in oil by using emulsifiers to help make the two phases mix.Emulsions are droplets or “bubbles” of liquid, known to those practicedin the art as “micelles,” suspended in another liquid with which thefirst liquid will not mix. The micelles are often called the“discontinuous phase” and the suspending liquid is called the“continuous phase.”

In the case of polyacrylamide emulsions, the polyacrylamide polymer isdissolved in the discontinuous phase, in this case, the water phase,while the continuous phase is oil. This is known as a water-in-oil (W/O)emulsion or a reverse emulsion. This type of emulsion keeps the polymerin small packets of water, which burst open when the emulsion comes intocontact with water. Polyacrylamide-based W/O emulsions disperse well inwater with vigorous stirring, and are used prevalently in watertreatment.

Such emulsions are also used, among other things, in pesticide tankmixtures to aid in preventing drift and increasing deposition on targetspecies. The problems with W/O emulsions are that they form solid lumpsand other forms when the emulsion is added to water with little or noagitation or if the water-to-emulsion ratio is too low. Also, emulsionsare inherently unstable and will eventually break or separate into oiland water layers. The oil rises as a layer, and the water layer sinks.Since the polymer chains are now free to combine, because they are notseparated by the oil “walls” (that is the oil and water separation ordividing line), they combine to form large lumps.

The polyacrylamide polymer itself comes in several types, defined byelectrical charge of the polymer chain. The polyacrylamide polymer maybe nonionic, anionic or cationic. The cationic form is commonly used inwater treatment. In the agricultural applications, the cationic, orpositively charged polymer, is rarely used, as it has a deleteriouseffect on aquatic wildlife. The nonionic or uncharged form is a reactionproduct of pure acrylamide, forming an uncharged, but water-solublepolymer that is quite inert in the environment.

Acrylamide is co-reacted with other monomers to form the cationic oranionic forms. To form the anionic polymer, acrylamide is most oftenreacted with an acrylate monomer that is further reacted so that itbecomes negatively charged. The nonionic and anionic polymers havedifferent properties. At lower levels in water, the anionic polymersbuild properties, such as viscosity, faster. Anionic polyacrylamidepolymers are compatible with other charged molecules, such as arecontained in fertilizers. However, they can react undesirably withcertain other charged molecules. Thus, nonionic polyacrylamides are usedin situations where the anionics are incompatible with other molecules.

The amount of charge is measured as a percent of the comonomer added.Thus, a polyacrylamide that is 30% acrylate and 70% acrylamide is calleda 30 percent-charged polymer. This percentage may be expressed as weightor mole percent, depending on the manufacturer. Typically, if thepolymer is a combination of the two monomers, the acrylic acid portionis reacted with base to form the acid salt. The polymer is thenconsidered to be charged.

Microemulsions are a very recent, commercially available development. Amicroemulsion is a special type of emulsion that has the same basicstructure as traditional emulsions, except that the droplets aresmaller. Smaller droplets, by virtue of the solution physics involved,are very stable and the droplets do not combine or separate in solutionsas traditional emulsions do. Microemulsions are also virtually clear,while sometimes having only a slight haze, as opposed to standardemulsions which are typically milky white.

Polyacrylamide microemulsions have their own disadvantages, however. Theprevalent disadvantage of a polyacrylamide microemulsion is that if itis combined with water or aqueous solutions, the polyacrylamidemicroemulsion will tend to form a skin at the surface that drasticallyreduces water diffusion, such as the diffusion of oil and/or emulsifiercombination into the water phase. This is due to the fact that there arevery many small aqueous droplets near the surface of the emulsion. Whenthe small aqueous droplets are combined with water, water diffusesquickly across the discontinuous phase and swells the micelles nearestthe surface. The micelles swell, combine, burst and rupture, in thatorder.

This almost instantaneous bursting of many of the droplets entangles thepolymer on the surface of the microemulsion and forms a barrier, which,in turn, slows diffusion of water further into the microemulsion anddispersion of the rest of the polymer. This phenomenon, sometimes knownas “skin” or “skinning,” causes the same problems that traditionalemulsions have in terms of dispersion and clean out.

Observers of microemulsions may actually observe that they are clear andtherefore question the ability of the product to do the job intended orobserve the presence, in this case, of polymer until the product isadded to water, which causes the characteristic milky appearance andslimy feel of polyacrylamide emulsion added to water appear.

While each of the polymers and the delivery systems has distinctadvantages, certain applications create great disadvantages for allpolymers. For example, in agricultural fields that are watered usingpivot irrigation, the polymer polyacrylamide is known to have beentested and shown to be effective at reducing the need for water.However, handling of the traditional emulsion, which is, thus far, theonly economical form for this application, can plug pumps, nozzles,screens, or other apparatus, when the tedious clean out proceduresnecessary following application and if not done properly can lead to thelumping process described above. Microemulsions have been tested in thisprocess and have been found to have the same problems because of theskinning described above.

Moreover, as noted, polyacrylamide requires surfactant and/or emulsionssystems useful for admixing the polyacrylamide to form stablemicroemulsions. Specifically, a surfactant or emulsion system should beuseful to effectively stabilize the aqueous discontinuous phase in oilto prevent phase separation and other like problems. The presentinvention provides emulsifier systems for stabilizingpolyacrylamide-containing microemulsions.

Water repellant soils may cause serious issues when attempting toenhance the ability of plants to uptake water and other materials, suchas fertilizers and/or pesticides. Specifically, water-repellant soilstypically retard water infiltration into the soil matrix rendering thesoil impervious to water penetration leading to underutilizedapplication or misapplication moving away from the target area. Runoffof applications of fertilizers and/or pesticides, as well as soilerosion may result, especially during heavy rainfalls and/or irrigationconditions, causing fertilizers and/or pesticides to flow into watersystems, such as reservoirs, lakes and rivers. Surfactants may beutilized to allow water infiltration of water-repellant soils, but manysurfactants tend to burn plants or cause other like damage to plants,such as agricultural products, growing in the water-repellant soils.

Another form of water-repellant soil is so-called “crusted” soils, suchas soils that have high amounts of organic matter built up on or nearthe surface of the soils. The crust may act as a barrier for thepenetration of water, especially aqueous systems, which would be usefulfor providing water, fertilizers and/or pesticides to the root systemsof plants.

Because it may be difficult to deliver pesticides and/or fertilizers toroots through water-repellant soils, known methods of deliveringmaterials, such as pesticides specifically, may include boring intotrees or other vegetation to deliver the useful materials. Of course,boring causes damage to trees and other vegetation, thereby weakeningthe trees or other vegetation.

It is generally known that ethylene oxide/propylene oxide (EO/PO) blockcopolymer has useful properties for wetting soils, for example,especially when used in agricultural, turf, ornamental or othercompositions, especially on water repellant soils. However, EO/PO isnotoriously difficult to mix into oil-containing systems.

EO/PO block copolymer has heretofore not been combined with W/Oemulsions of polyacrylamide to obtain the useful properties of both thepolyacrylamide (water retention) and the EO/PO block copolymers (waterpenetration). This is so because one would not expect EO/PO blockcopolymer to be useful in mixing in such a system because of itsinherent incompatibility with oils. An EO/PO block copolymer is a longchain polymer made with ethylene oxide and propylene oxide portions.Thus, one would not expect EO/PO to mix well in W/O emulsions,especially due to the fact that EO/PO block copolymer hydrophobicportion, the PO block portion, is not a good lipophile or oil-lovingmolecule. Since, typically, emulsifiers (molecules that contain bothwater-loving and oil-loving portions) must contain a strong lipophile tobe an effective ingredient in an emulsions or microemulsion, one ofordinary skill in the art would not look to include EO/PO blockcopolymer in a W/O emulsion, especially in combination with thepolyacrylamide.

SUMMARY

A first aspect of the present invention provides a water-in-oilmicroemulsion, including a polyacrylamide, a fatty acid, a surfactant,an oil continuous phase, and an aqueous discontinuous phase in the oilcontinuous phase. The fatty acid includes a tall oil fatty acid, oleicacid, or a combination of a tall oil fatty acid and oleic acid. Thewater-in-oil microemulsion contains 6 to 48 parts by weight of thepolyacrylamide, 30 to 62 parts by weight of the fatty acid, and 20 to 44parts by weight of the surfactant per 100 parts by weight of thepolyacrylamide, the fatty acid, and the surfactant combined.

According to a second aspect of the present invention, a method ofdispersing a water-in-oil microemulsion into an aqueous medium andapplying the water-in-oil microemulsion dispersed in the aqueous mediumin an agricultural application is provided. The water-in-oilmicroemulsion includes a polyacrylamide, a fatty acid including a talloil fatty acid and/or oleic acid, a surfactant, and an oil continuousphase, an oil continuous phase, and an aqueous discontinuous phase inthe oil continuous phase, wherein the water-in-oil microemulsioncontains 6 to 48 parts by weight of the polyacrylamide, 30 to 62 partsby weight of the fatty acid, and 20 to 44 parts by weight of thesurfactant per 100 parts by weight of the polyacrylamide, the fattyacid, and the surfactant combined. Micelles of the water-in-oilmicroemulsion are allowed to burst in the aqueous medium. The aqueousmedium with the water-in-oil microemulsion dispersed therein is appliedto at least one seed, at least one growing crop, at least one forestarea, at least one turf or other vegetation, at least one soil, at leastone crop, or a combination thereof.

A third aspect of the present invention provides a method of dispersinga water-in-oil microemulsion into an aqueous medium and applying thewater-in-oil microemulsion dispersed in the aqueous medium. Thewater-in-oil microemulsion includes a polyacrylamide, a fatty acidincluding a tall oil fatty acid and/or oleic acid, a surfactant, and anoil continuous phase, an oil continuous phase, and an aqueousdiscontinuous phase in the oil continuous phase, wherein thewater-in-oil microemulsion contains 6 to 48 parts by weight of thepolyacrylamide, 30 to 62 parts by weight of the fatty acid, and 20 to 44parts by weight of the surfactant per 100 parts by weight of thepolyacrylamide, the fatty acid, and the surfactant combined. Micelles ofthe water-in-oil microemulsion are allowed to burst in the aqueousmedium. The aqueous medium with the water-in-oil microemulsion dispersedtherein is applied to at least patch of bare ground, at least oneroadside, at least one industrial area, at least one right-of-way, atleast one water management area, at least one waterway, or a combinationthereof.

According to a fourth aspect of the invention, a method of making awater-in-oil microemulsion is provided. The method involves combining ananoemulsion of a polyacrylamide with a fatty acid including a tall oilfatty acid and/or oleic acid, a surfactant, and an oil continuous phaseto form a microemulsion comprising an oil continuous phase and anaqueous discontinuous phase in the oil continuous phase, wherein thewater-in-oil microemulsion contains 6 to 48 parts by weight of thepolyacrylamide, 30 to 62 parts by weight of the fatty acid, and 20 to 44parts by weight of the surfactant per 100 parts by weight of thepolyacrylamide, the fatty acid, and the surfactant combined.

Other aspects of the invention, including apparatus, devices, systems,processes, and the like which constitute part of the invention, willbecome more apparent upon reading the following detailed description ofthe exemplary embodiments.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The accompanying drawings are incorporated in and constitute a part ofthe specification. The drawings, together with the general descriptiongiven above and the detailed description of the exemplary embodimentsand methods given below, serve to explain the principles of theinvention. The objects and advantages of the invention will becomeapparent from a study of the following specification when viewed inlight of the accompanying drawings, wherein:

FIG. 1 is an equilateral triangular graph of results of examplesreported herein; and

FIG. 2 is another equilateral triangular graph of results of furtherexamples reported herein.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS AND EMBODIED METHODSOF THE INVENTION

In accordance with exemplary embodiments described herein, there isprovided a water-in-oil microemulsion including a polyacrylamide, afatty acid, a surfactant, an oil continuous phase, and an aqueousdiscontinuous phase in the oil continuous phase. The microemulsion maycontain other components, such as, by way of example, pesticides and/orfertilizers, that may be delivered to trees, plants or other vegetation.For the purpose of this disclosure, “pbw” means parts by weight.

Polyacrylamide

The present invention comprises an effective amount of polyacrylamidecopolymer in a W/O microemulsion or nanoemulsion to impart desiredcharacteristics, especially when combined with an aqueous medium, suchas water, for use thereof. Specifically, the polyacrylamide may bedesired to hold and/or retain water.

Microemulsion compositions according to exemplary embodiments include aneffective amount of polyacrylamide, generally in the form of apolyacrylamide microemulsion or nanoemulsion. The polyacrylamide ispresent in an amount of 6 to 48 pbw per 100 pbw of the polyacrylamide,the fatty acid, and the surfactant combined. In the content of theentire W/O microemulsion, the polyacrylamide may constitute, forexample, up to about fifteen percent of the total weight of the W/Omicroemulsion. This content may then be further diluted in water at thetime of use to impart the desired characteristics of the polymer to thewater phase or to the material to which the water phase is applied, asdescribed in more detail below. The range of polyacrylamide content maybe about one percent (1%) to about ten percent (10%) by weight, morespecifically about two percent (2%) to about eight percent (8%) byweight of the total weight of the W/O polyacrylamide. As should beapparent to one of ordinary skill in the art, the polyacrylamidemicroemulsion or nanoemulsion component may be any emulsion that impartsthe effective amount of polyacrylamide solids, as described above. Forexample, a typical polyacrylamide emulsion useful for the presentinvention includes Kemira Superfloc brand polyacrylamide nanoemulsionhaving twenty two percent (22%) polyacrylamide copolymer solids content.However, any other polyacrylamide emulsion composition may be utilizedas apparent to one of ordinary skill in the art to arrive at the desiredpolyacrylamide content.

The present invention requires less active ingredient of polyacrylamidecontent to allow bubbles to disperse in the water phase. Thus, as noted,it may be preferred for some applications for the composition to have nogreater than about fifteen percent (15%) by weight polyacrylamidecopolymer solids, because compositions having greater than about fifteenpercent (15%) by weight polyacrylamide copolymer solids may be difficultto disperse in the aqueous phase. Thus, utilizing less polyacrylamidecopolymer solids during manufacturing is a way to achieve this goal. Acountervailing consideration is that more polyacrylamide copolymersolids imparts more of the desired property of water retention, thushigher amounts of polyacrylamide copolymer solids, such as higher thanfifteen (15%) by weight, may be desired.

Anionic polyacrylamide is particularly useful in the present invention.The charge of the polyacrylamides may be from zero percent (0%) to aboutforty percent (40%) by weight, which may be resultant because thereaction forming the polyacrylamide generally starts with about zeropercent (0%) to about forty percent (40%) by weight acrylic acid or acidsalt. The polymer that may be formed with acrylic acid or an acid saltmonomer is called anionic polyacrylamide because the polymer itselfcontains a negative charge, which is balanced by a cation, usuallysodium. A polymer made with little or no acid or acid salt is considerednonionic polyacrylamide because the polymer essentially contains nocharge. The range of charge disclosed herein is generally necessary toensure compatibility of the polymer with the various types ofingredients in the tank mixes. Higher or lower charge may directlyaffect compatibility, as the higher charge may be generally morecompatible with fertilizers, and the lower charge may be more compatiblewith other types of charged species that may form an insoluble salt withan anionic polymer.

The weight average molecular weight of the polyacrylamide may be up toabout thirty-five megagrams (35 Mg) per mole. More preferably, theweight average molecular weight of the polymer may be up to about thirtymegagrams (30 Mg) per mole. Most preferably, the weight averagemolecular weight of the polymer may be up to about twenty five megagrams(25 Mg) per mole. The range of concentrations disclosed herein may allowfor the maximum flexibility in the use of the polymer. Ultra-highmolecular weight polymers build viscosity quickly and are highly stablein soil. High viscosity and high stability are, generally, two desirableproperties for the microemulsions disclosed herein.

Oil

The microemulsions of the exemplary embodiments are W/O emulsions. Anyoil may be utilized that may be effective in forming the microemulsions,as described herein. The oil in the water-in-oil microemulsion may bemethylated soybean oil (“MSO”) or soy methyl ester (“SME”), or aparaffin oil, which may be utilized to form the stable microemulsion ofpolyacrylamide and EO/PO block copolymer. However, any effective oil maybe used in an effective amount.

For example, oils that may be used to form the stable microemulsions maybe: 1) petroleum oils, more preferably, paraffinic oils (e.g., whiteoils) and naphthalenic oils, and/or 2) naturally occurring oils such asseed oils, such as, cottonseed, canola, soybean, corn, palm kernel orcoconut oil, and/or 3) derivatives of naturally occurring oils such asthe methyl or ethyl esters or methylated or ethylated derivatives of theabove-named oils.

A microemulsion having polyacrylamide may be formed utilizing, asstarting materials, a polyacrylamide nanoemulsion and an amount ofsurfactant, such as an EO/PO copolymer (discussed below), that iscombined with a methylated soybean oil or paraffin oil to form a W/Omicroemulsion.

The oils, taken singly or in mixtures as named, herein may constitute upto about ninety percent (90%) by weight of the composition. Morepreferably, the oils, taken singly or in mixtures as named, herein mayconstitute from about twenty (20%) to about eighty percent (80%) byweight of the composition. Most preferably, the oils, taken singly or inmixtures as named, herein may constitute about thirty percent (30%) toabout seventy percent (70%) by weight of the composition.

Stabilizers

For the two phases of microemulsions to mix or “emulsify,” a set ofemulsifiers may be used. Generally, emulsifiers contain two areas orregions within the molecule, one that is hydrophobic and one that ishydrophilic. This structure therefore acts as “glue” that holds the twoimmiscible phases together, and interconnects the two phases together bygoing to the interface between the two phases and bridging the two, withthe hydrophobic portion sticking into or otherwise contacting the oilphase and the hydrophilic portion sticking into or otherwise contactingthe aqueous phase.

Exemplary embodiments described herein contain at least one fatty acidand at least one nonionic surfactant. This combination is unique in itsability to bring the two phases together and work together to stabilizethe microemulsion. The one or more fatty acids and the one or moresurfactants come together to form an easily water-dispersiblemicroemulsion product with fewer handling issues. The terms “surfactant”and “emulsifier” may typically be used interchangeably, since allemulsifiers are surfactants and most surfactants are emulsifiers. Theseterms tend to differentiate the jobs each performs rather than anystructural or chemical differences between them.

The presence of the fatty acids may be preferable in terms of dispersionas the fatty acids may act as the main contributor to slowing thediffusion of water and, therefore, bursting of the micelles into thewater phase when dispersed in water.

This effective use of fatty acids is surprising, because it is knownthat ionic surfactants do not stabilize water-in-oil (W/O) emulsionswell. The book “Chemistry and Technology of the Cosmetics and ToiletriesIndustry”, D. F. Williams, W. H. Schmitt, Second Ed., Springer, 1996, p.31, states, “A limited number of W/O emulsifiers are available. This isbecause ionic emulsifiers will not generally work in the case of W/Oemulsions.” Since fatty acids can form, and often are used as,negatively charged species, they are generally considered ionicemulsifiers.

The fatty acid may be one or more selected from the group consisting ofC₈ to C₃₀ fatty acids. Such acids include, but are not limited to,myristic, lauric, palmitic, stearic, oleic, and linoleic acids andmixtures of fatty acids derived from natural sources such as coco,lauryl, palm, soy, cottonseed and tall oil fatty acids. The fatty acidmay include at least one fatty acid whose major content is C₁₈ fattyacids such as soy and tall oil fatty acids. An effective amount of fattyacid, as described herein, may be utilized. The fatty acid content maybe, for example, up to about thirty percent (30%) by weight, about onepercent (1%) to about twenty five percent (25%) by weight, or about fivepercent (5%) to about twenty percent (20%) by weight. The water-in-oilmicroemulsion may contain 6 to 48 parts by weight of the polyacrylamide,30 to 62 parts by weight of the fatty acid, and 20 to 44 parts by weightof the surfactant per 100 parts by weight of the polyacrylamide, thefatty acid, and the surfactant combined.

In an exemplary embodiment, the fatty acid is a tall oil fatty acid, andthe water-in-oil microemulsion contains 6 to 40 parts by weight of thepolyacrylamide, 30 to 62 parts by weight of the tall oil fatty acid, and20 to 44 parts by weight of the surfactant per 100 parts by weight ofthe polyacrylamide, the tall oil fatty acid, and the surfactantcombined. In another exemplary embodiment using tall oil fatty acid, thewater-in-oil microemulsion contains 8 to 32 parts by weight of thepolyacrylamide, 30 to 60 parts by weight of the tall oil fatty acid, and24 to 43 parts by weight of the surfactant per 100 parts by weight ofthe polyacrylamide, the tall oil fatty acid, and the surfactantcombined.

In a further exemplary embodiment, the fatty acid is oleic acid, and thewater-in-oil microemulsion contains 10 to 48 parts by weight of thepolyacrylamide, 30 to 60 parts by weight of the oleic acid, and 20 to 39parts by weight of the surfactant per 100 parts by weight of thepolyacrylamide, the oleic acid, and the surfactant combined. In still afurther exemplary embodiment using oleic acid, the water-in-oilmicroemulsion contains 16 to 32 parts by weight of the polyacrylamide,30 to 60 parts by weight of the oleic acid, and 24 to 38 parts by weightof the surfactant per 100 parts by weight of the polyacrylamide, theoleic acid, and the surfactant combined.

Preferably, the nonionic surfactants include at least one surfactantselected from the group consisting of ethoxylated surfactants,nonylphenol ethoxylates or alcohol ethoxylate or other ethoxylatedsurfactants. Better results may be obtained with nonylphenol ethoxylatesor alcohol ethoxylate surfactants. The best results may be obtainedwith, most preferably, alcohol ethoxylates. The nonionic surfactantcontent may be up to about thirty percent (30%) by weight, or about onepercent (1%) to about twenty five percent (25%) by weight, or about fivepercent (5%) to about twenty percent (20%) by weight based on the totalweight of the microemulsion.

Another surprising property of the nonionic surfactant ingredient is theuse of a nonionic surfactant or a combination of nonionic surfactantswith a relatively high hydrophilic-lipophilic balance (HLB). HLB is thenature of a surfactant to have a balance between aqueous and nonaqueousphases. A low HLB surfactant has a high affinity for oily or nonaqueousphases and is generally highly insoluble in water. A high HLB valuesurfactant may generally have a high affinity for water and may formclear mixtures with water, even at high concentrations. Fatty acidsgenerally have a long lipophilic chain terminated in a carboxylic acidmoiety that is hydrophilic. The lipophilic portion generally dominatesthe molecule, however. Nonionic surfactant may generally have acarefully controlled HLB and range across the entire spectrum of HLB.Addition of the proper nonionic surfactant may allow the correct HLBvalue of the overall surfactant to be reached.

A nonionic surfactant or at least one nonionic surfactant in acombination of surfactants may have an HLB greater than 9.0, or about9.0 to about 20, or about 9.3 to about 15. Nonionic surfactant and/or acombination of surfactant with at least one nonionic surfactant having ahigher HLB are desirably used. By contrast, the fatty acids of thecompositions may be very low HLB emulsifiers.

EO/PO Block Copolymer

The W/O microemulsion optionally may contain an EO/PO block copolymer.An amount of EO/PO block copolymer is optionally included in thecompositions to impart improved water penetration, especially inhydrophobic media, such as in water repellant soils or crusted soils.Generally, an effective amount of EO/PO block copolymer may be up toabout forty percent (40%) by weight, more preferably, about two percent(2%) to about thirty five percent (35%) by weight, most preferably aboutthree percent (3%) to about thirty percent (30%) by weight.

The EO/PO block copolymer may include the straight block polymericglycols obtained, for example, by the addition of ethylene oxide (EO) ona condensation product of propylene oxide (PO). Reverse blockcopolymers, which are also acceptable for use, may be prepared byreacting EO with itself to provide a hydrophile of designated molecularweight. PO is then added to obtain hydrophobic blocks on the outside ofthe molecule. Reversing the hydrophobic and hydrophilic blocks createspolymers that are similar to the regular EO/PO block copolymers, butwith some important differences. While the EO/PO straight blockcopolymers tend to be better emulsifiers and dispersants and generallycover a broader range of molecular weights, the reverse block copolymersgenerally have lower foaming, greater defoaming, and reduced gellingtendencies.

The amount of polyacrylamide and optional EO/PO block copolymer utilizedin an emulsion of the present invention may preferably be effective andeconomically viable. Delivering a solution that has too low polymercontent may mean delivering too much water or other ineffectiveingredient to a site, thereby causing shipping costs to be too high.

However, a polymer level that is too high may also be detrimental. It iswell known to users that handle emulsions that adding a small amount ofwater to any emulsion may break the emulsion and cause it to gel. Thegelling may cause a large, thick mass to form that does not dissolveeasily in water and which may have to be stirred for days to dissolvecompletely. The lower level of polymer combined with the otherelements/ingredients of the present invention may significantly reducegelling.

Other Components

The microemulsions described herein may further include effectiveamounts of other components. Specifically, the present invention may actas a delivery system for effective amounts of components having aspecific purpose, such as pesticides, such as insecticides, fungicidesand other like pesticides, and/or fertilizers. For example, thecompositions of the present invention may be useful for wetting and/orpenetrating hydrophobic soils. Thus, the compositions of the presentinvention may be particular useful to deliver water and/or othercomponents, such as pesticides and/or fertilizers to roots of vegetationthrough hydrophobic soils. Preferably, these other components may beadmixed into the compositions of the present invention in theirconcentrated forms, prior to the addition of water. However, it shouldalso be apparent to those of ordinary skill in the art that these othercomponents may added after diluted with water and prior to delivery to adesired area or location, such as to hydrophobic soil.

The microemulsion may be achieved in at least two ways. A first way isto classically create the microemulsion using well-known techniques.These techniques are often employed in manufacturing microemulsions.However, the objective is almost always to create a microemulsion withthe highest content of active ingredient possible. Thus, thesemicroemulsions may classically be more than 15% polyacrylamide foreconomy of transport and value.

However, another way to create the microemulsion involves diluting thecommercially available material with higher concentrations of oil andemulsifier. The commercially available microemulsion is relativelyinexpensive compared to the cost of forcing a special reaction.Therefore, the “dilution method” of making a microemulsion is relativelysimple and inexpensive, while effectively reaching the same objectivesat less cost.

The benefits of certain exemplary embodiments of the present inventionare at least two-fold. First, the microemulsions are more stable thannormal emulsions, as is generally disclosed above. Thus, long-termstorage may be possible and even likely, as opposed to other emulsions,which tend to have long-term storage problems. The second benefitinvolves the amount of polymers and the solutions in which they aredelivered.

The exemplary embodiments and methods disclosed herein may address theproblem of the formation of microemulsion “skin” by production of adilute, but not too dilute, and stable microemulsion. This may beaccomplished, in a practical and economic sense, through dilution of themicroemulsion with oil. The addition of oil may create a thickercontinuous layer through which water and water droplets must pass. Thismay slow diffusion of water from the bulk liquid into the droplets. Themicelles, therefore, may swell more slowly. Slower dispersion of thedroplets at the surface of the microemulsion and slower swelling of thedroplets in the microemulsion may mean that the surface skin does notform when the microemulsion comes in contact with water.

However, addition of oil to the microemulsion alone may be inadequate.If oil is added directly to a typically manufactured polyacrylamidenanoemulsion, or any other emulsion for that matter, an unstableemulsion results and a discontinuous layer may separate from thecontinuous layer. The addition of further ingredients, typically moreemulsifier, may be warranted to ensure a stable, easily-dispersedmicroemulsion having polyacrylamide content.

Exemplary embodiments disclosed herein may address the potentialinstability by addition of emulsifiers to form stable microemulsions.These emulsifiers balance the water and oil phases, and may becompatible with the emulsifiers that may be typically used inmicroemulsions. However, with the addition of more oil, the balance ofthe emulsifiers may be adjusted to coincide with the water/oil ratiochange.

Of course, the ideal amounts of each component may depend on the amountsof the other components within the compositions. For example, the amountof fatty acids and/or surfactants needed to create stable microemulsionsmay vary depending on the ratio of oil to aqueous phase and also on theamount of polymer present in the aqueous phase. However, the fatty acidmay not, typically, be used alone, i.e., without the surfactant. Thefatty acid may preferably be balanced with one or more surfactants toensure compatibility with the aqueous phase.

The addition of one or more supplementary nonionic surfactants may bedesired, for example, to counteract or balance the possibility that theaddition of fatty acid will throw off the balance between thehydrophilic and hydrophobic phases. Nonionic surfactants with a mediumto high HLB, such as, for example, a nonionic surfactant having an HLBabove about 9.3, are particularly useful.

The exemplary embodiments, and in particular the amount of oil, theamount and type of surfactant(s), the amount of polyacrylamidecopolymer, and amount of fatty acid may be controlled to provide aneconomical, easy-to-handle solution. Exemplary embodiments disclosedherein may disperse substantially homogeneously in water, withsubstantially no “lumping” as that term is used in the art. Theskinning, lumping and clumping that is a problem with othermicroemulsions and standard emulsions generally does not form. Yet,there is enough surfactant for the product to disperse into the waterphase through a mechanism that releases the water droplets into theadded water more slowly. Without being bound by theory, it is thoughtthat the slower release may allow the polymers to disperse into thewater to which it is added before other water droplets nearby in themicroemulsion burst open or combine, thereby avoiding the entanglementthat normally causes skinning or lumps.

Also, exemplary embodiments disclosed herein may be generally clearer,in terms of appearance, than other emulsions or microemulsions. Ingeneral, microemulsions typically have a slight haziness. They can begenerally viewed through easily, but do have minor, but definitive,cloudiness. Exemplary embodiments disclosed herein may provide solutionsthat are crystal clear and stable.

The microemulsion of exemplary embodiments may disperse into the aqueousphase well because of the combination of oil and surfactants thatsurround the water droplets that may contain the polymer. If the amountand/or ratios of oil and surfactants are not correct, at least one oftwo things may occur.

First, if the mixture contains too much oil phase, the dispersion ofpolymer into the water may be slowed. Aside from this physical problem,there may also be financial consideration of utilizing too much oilphase. Microemulsions formed with too much oil phase will not,generally, have a viscosity issue, as the aqueous solutions ofpolyacrylamide typically do, but will become uneconomical for the samereason that the aqueous polymer solutions will be uneconomical. Therewill generally be too little polyacrylamide present to be effective,and, additionally, the solution surrounding the polymer will typicallybe more expensive than just plain water.

Second, if enough oil is not added or the oil/emulsifier ratio is toohigh in the amount of emulsifier or the emulsifier is too water soluble,the micelles will swell and burst too quickly, causing problems ofskinning and lumping. After the stable microemulsion is produced, theproduct must be able to be utilized by diluting the product in water orwater-based mixtures for application. The precise amounts of the variouscomponents of the compositions described herein may be determined by oneof ordinary skill in the art without undue experimentation.

The ability to use exemplary embodiments disclosed herein properly isgreatly enhanced over other solutions. The microemulsion may be added toany aqueous solution with a modicum of stirring or movement. It willdisperse well, not forming lumps or clumps. The means of addition may bein the form of pouring, as into a container or tank, or by injection, asinto a pipeline using a pump and check valve, or by any other means ofaddition apparent to one of ordinary skill in the art where themicroemulsion is dispersed into an aqueous liquid.

In another embodiment, compositions embodied herein may be spray treatedonto dry carriers that may then be stored for extended periods of time.In addition, spray treating onto a dry carrier may enhance the ease ofhandling the compositions. When desired for use, the dry carrier havingthe compositions of the present invention spray treated thereon may becombined with water to form a dispersion for application thereof.

There are multiple uses for the exemplary embodiments disclosed herein.In use, the compositions may be used, for example, by dispersing themicroemulsion in an aqueous media when ready for use. Exemplary uses aredescribed below.

One use is in irrigation. Dispersions (or solutions) of themicroemulsion may be pumped, using an injection pump or piston or otherdesign, into a pipe carrying irrigation water to a pivot or otherdelivery system. Because of the superior dispersion properties ofexemplary embodiments described herein, there is no need to furthertreat or add other ingredients. The injection is followed directly by awater rinse. The water rinse may easily move through the pump withoutcomplications.

Another use is in an agricultural or non-agricultural spray tank mixcontaining pesticides. Solutions of the microemulsion may be addeddirectly into the tank while the ingredients in the tank are beingstirred. Again, the dispersion is generally very easy, not forming lumpsor clumps in accordance with exemplary embodiments disclosed herein.

Solutions of the microemulsion may also be used in pesticide tank mixesfor several reasons. First, the solutions may provide the ability tocontrol the deposition of a pesticide to a target species. The presenceof a deposition aid or drift control product may generally be requiredin the future to control drift in order to reduce drift of pesticidesonto non-target species.

The exemplary compositions disclosed herein may be added into an aqueousmedium to impart the desired properties. The aqueous medium may then beused in a desired fashion. Such uses may include, but are not limitedto, applying the microemulsion to at least one seed, at least onegrowing crop, at least one patch of bare ground, at least one roadside,at least one industrial area, at least one soil erosion area, at leastone right-of-way, at least one forest area, at least one turf or othervegetation, at least one soil, at least waterway, at least one crop, atleast one fertilizer, at least one water management area or variouscombinations thereof.

In addition, the polyacrylamide microemulsion in a W/O dispersion,particularly when the EO/PO block copolymer is included, may beparticularly useful in applications whereby wetting is required. Forexample, in soils having poor wettability, the compositions disclosedherein may be particularly useful for wetting of poorly wettable soils.Moreover, the compositions may be useful for imparting anti-crustingproperties, such as helping to prevent the buildup of organic materialthat may crust and otherwise create a barrier to water penetration.

Forming the aqueous dispersions of the present invention may beaccomplished in any suitable fashion. Typical forming processes mayinclude, but are not limited to, forcing the composition into theaqueous medium by at least one operation selected from the groupconsisting of stifling the aqueous medium and the composition, pumpingthe aqueous medium and the composition through a pipe or stifling it ina tank, pouring the composition into a tank containing the aqueous mediaand injecting the composition into the tank.

The following non-limiting examples are intended to illustrate thepresent invention without unduly limiting the scope of the presentinvention.

EXAMPLES

The microemulsions of the exemplary embodiments are easily pumped usingstandard piston, check valve and other pumps because the microemulsionremains fluid and well below the maximum viscosity of the pumps used inagricultural and irrigation applications. That maximum viscosity isabout 1000 cps. In fact, emulsions and microemulsions are used becausethey can deliver large amounts of polymer in a concentrated form to theinjection site at low viscosities.

However, when the pump needs to be cleaned out, for example, in order todeliver the next product, such as fertilizer, the pump generally must becleaned out with some fluid that is readily available, inexpensive, andpreferably environmentally safe. The preferred cleanout fluid is water,which is readily available at well-heads. Experience has shown that withstandard emulsions and previous micro- and nanoemulsions that cleaningthe pump with water causes the pump to plug. This is because the mixinginterface between the emulsion and the water goes through a viscositycurve as the water and emulsion mix. The external water diffuses to thewater micelles, causing them to swell, combine and burst. As the watermicelles swell and combine, the viscosity increases and the polymermolecules, once separated by the oil continuous phase, entangle. Thisentanglement, on a large scale, causes a dramatic increase in viscosity.As an example of the sorts of viscosities that can be achieved, thereare commercial products that, when combined with water a rate of 1-2%pure polymer, reach 2000 cps or more. At higher levels, the polymerbecomes too thick to pour out of a bottle because the solution can reach4500 cps. The more polymer that is added, the higher the viscosity.

So, when the polymer is mixed with water in the pump, it goes through atransition where the amount of polymer starts out at its maximum leveland decreases as water diffuses in the system. However, the swelling,combining and bursting on a large scale can cause polymer levels thatfar exceed that 1-2% level that make the polymer solution pumpable andfar exceed the ability of a pump that is capable of pumping a solutionat about 1000 cps to be able to pump. While one can imagine that amicroemulsion polymer may contain 2, 4, 8, 16 or 20% or more polymer,the local water diffusion would cause local polymer levels at theinterface to reach much higher levels when the oil phase is displaced.This causes the dramatic viscosity increase that can make the polymerunpumpable.

As water diffuses and the material becomes thicker, water diffusionslows dramatically because physical mixing cannot be achieved in thepump. Only when the amount of water sufficiently dilutes, and thereforebegins to untangle the polymer, does the viscosity begin to decrease.This cause a viscosity curve at which some maximum is reached at acertain percentage of water less than 100% but greater than zero. If themaximum viscosity achieved is lower than the pump can handle, the pumpwill continue to pump the fluid. If the viscosity of the mixed water andmicroemulsion goes above the pump's maximum viscosity, the fluid willstop moving and the pump will be plugged.

A system that would slow down diffusion of the water to the micelles orreduce swelling, combining and bursting would reduce the level ofviscosity achieved at the interface. Any test that can test the maximumviscosity achieved during the mixing of the water and microemulsionwould give an indication of the maximum viscosity that could beexperienced by a system.

In order to mimic the diffusion and mixing, water was combined atvarious levels to determine the viscosity curve of the microemulsion.Three formulation variables were tested in order to examine the effectof those variables vis-à-vis the maximum viscosity. These variables werepercent nonionic surfactant, percent fatty acid, and percent polymer.These materials were mixed in various ratios. Various combinations ofthese three materials were mixed and observed for clarity, an indicationof stability. The clearer the mixture is, the more stable it will be. Acompletely clear mixture may be stable for years, a commerciallydesirable feature.

After the combinations were prepared, each was tested for viscosity bythe following procedure. 100 g of total solution was used in order totest the viscosity. Water was added to the prepared solution. The ratioof water and prepared solution were varied by adding 10, 20, 30, 40 and50% by weight water to the prepared polymer microemulsion. Freshmicroemulsion was used with each combination of water and microemulsion.In other words, separate samples that were 10% water and 90%microemulsion, 20% water and 80% microemulsion and so on, were prepared.Immediately after the water and microemulsion were combined, the mixturewas stirred for 1 minute using an overhead stirrer. After stirring, thewater/microemulsion mixture was immediately moved to a viscometer. Theviscometer was a Brookfield LVDV-1+ dynamic digital viscometer. Theviscometer was started and allowed to spin for one minute, after whichthe reading was taken. The viscometer, being digital, provides thereading directly in centipoise.

The data has four independent variables, i.e., the percentage of each ofthe three components and the percentage of water added for viscositytesting, and one dependent variable, i.e., the viscosity measured.However, only the maximum viscosity needs to be reported for eachwater/microemulsion combination. This is because, as stated above, ifthe viscosity remains less than 1000 cps at all water percentages, thenthe mixture remains pumpable. If the viscosity of thewater/microemulsion mixture goes over 1000 cps at any combination, thendiffusion, rather than mixing, becomes limiting and plugs the pump.Therefore, the maximum viscosity achieved is the determining factor forwhether a mixture will plug a pump or not.

Examples 1-13

Examples 1-13 contained a blend of E-4366 microemulsion (Kemira), talloil fatty acid, and Tergitol NP9.5 surfactant (Dow Chemical). Oil wasadded in an equal weight amount to bring the added oil content to 50weight percent. The percent by weight for each component was determined,taking into consideration the presence of additional surfactant presentin the Kemira product. The blends, weight percentages and measuredviscosities are reported below in Table 1. The viscosities are reportedin a triangular graph form in FIG. 1, which allows the reporting offour-dimensional data in two dimensions. Each side of the trianglerepresents a respective one of the three dependent variables—i.e., thepercentage of nonionic surfactant, fatty acid and polymer. The numbersplotted on the graph are the maximum viscosity achieved for thatmixture.

TABLE 1 Polyacrylamide TOFA Surfactant Viscosity EX. Blend (%) (%) (%)(cps) 1 80/10/10 36.4 20.7 42.9 58920 2 70/20/10 28.1 36.5 35.4 336 370/30/0 28.1 54.9 17.0 3120 4 50/30/20 16.2 44.4 39.4 978 5 50/40/1016.2 59.1 24.7 276 6 40/30/30 11.9 40.4 47.7 7972 7 40/60/0 11.9 80.97.3 2424 8 30/40/30 8.2 49.6 42.2 642 9  0/90/10 0 90 10 26880 1078/12/10 34.6 24.1 41.3 4548 11 76/14/10 32.8 27.5 20.2 (39.7%) 1371 1274/16/10 31.2 30.7 19.9 (38.1%) 831 13 28/52/20 7.6 63.4 23.8 (29.0%)1002

Examples 14-26

Examples 14-26 contained a blend of E-4366 microemulsion (Kemira), oleicacid, and NP9.5 surfactant (Kemira). Oil was added in an equal weightamount to bring the added oil content to 50 weight percent. The percentby weight for each component was determined, taking into considerationthe presence of additional surfactant present in the Kemira product. Theblends, weight percentages and measured viscosities are reported belowin Table 2. The viscosities are reported in a triangular graph form inFIG. 2, which allows the reporting of four-dimensional data in twodimensions. Each side of the triangle represents a respective one of thethree dependent variables—i.e., the percentage of nonionic surfactant,fatty acid and polymer. The numbers plotted on the graph are the maximumviscosity achieved for that mixture.

TABLE 2 Polyacrylamide Oleic Acid Surfactant Viscosity EX. Blend (%) (%)(%) (cps) 14 80/10/10 36.4 20.7 42.9 87400 15 70/20/10 28.1 36.5 35.4321 16 70/30/0 28.1 54.6 17.3 9360 17 50/30/20 16.3 44.3 39.4 1236 1850/40/10 16.2 59.1 24.7 348 19 40/30/30 11.9 40.4 47.7 69120 20 40/60/011.9 80.8 7.3 3444 21 30/50/20 8.2 62.0 29.8 1458 22 76/14/10 32.8 27.539.7 1068 23 74/16/10 31.2 30.7 38.1 762 24 48/42/10 15.3 60.9 23.8 139825 46/44/10 14.4 62.6 23.0 1428 26 28/52/20 7.6 63.4 29.0 1776

The results show an unexpected viscosity minimum based with acombination of fatty acids and nonionic surfactant is achieved. Inexamples that provided viscosities of 1000 cps or less, pumps containingthe emulsion may be cleaned via water flushing only. No specialpre-rinse with out between the polymer injection and water cleanout isrequired, and special pumps are not needed for irrigation injectionpurposes, thus overcoming previous generations of gumming and clogging.

Example 27

The following ingredients were combined to form a microemulsionconcentrate: paraffin oil—53% (Tolex RHT 70); polyacrylamidenanoemulsion—30% (Superfloc E 4366, 6.6% solids); tall oil fattyacid—10.2% (Mead Westvaco L5D); can be substituted with pine derivedoleic acid; EO/PO reversed block copolymer—3.4% (Pluronic 10R5 (BASF));nonylphenol ethoxylate—3.4% (NP 9.5). The above ingredients were addedto a container in the order specified above. The mixture was stirredcontinuously while the ingredients were added. A crystal clear, goldenmixture was formed.

Example 28

The following ingredients were combined to form a microemulsionconcentrate: paraffin oil—34% (Tolex RHT 70); polyacrylamidenanoemulsion—40% (Superfloc E 4366, 8.8% solids); tall oil fattyacid—10.2% (Mead Westvaco L5D); can be substituted with pine derivedoleic acid; EO/PO reversed block copolymer—3.4% (Pluronic 10R5 (BASF));nonylphenol ethoxylate—3.4% (NP 9.5). The above ingredients were addedto a container in the order specified above. The mixture was stirredcontinuously while the ingredients were added. A crystal clear, goldenmixture was formed.

Example 29

The following ingredients were combined to form a microemulsionconcentrate: methylated soybean oil (MSO)—80.91%; polyacrylamidenanoemulsion—9.87% (Superfloc E 4916, 2.17% solids); tall oil fattyacid—3.08% (Mead Westvaco L5D); can be substituted with pine derivedoleic acid; nonylphenol ethoxylate—3.07% (NP6); EO/PO reversed blockcopolymer—3.07% (Pluronic L61 (BASF)). The above ingredients were addedto a container in the order specified above. The mixture was stirredcontinuously while the ingredients were added. A crystal clear, goldenmixture was formed.

Example 30

The following ingredients were combined to form a microemulsionconcentrate: methylated soybean oil (MSO)—56.44%; polyacrylamidenanoemulsion—9.87% (Superfloc E 4916, 2.17% solids); tall oil fattyacid—1.85% (Mead Westvaco L5D); can be substituted with pine derivedoleic acid; nonylphenol ethoxylate—1.84% (NP6); EO/PO reversed blockcopolymer—30% (Pluronic L61 (BASF)). The above ingredients were added toa container in the order specified above. The mixture was stirredcontinuously while the ingredients were added. A golden mixture with avery slight haze was formed.

Example 31

An amount of the composition of Example 30 (65.22%) was mixed with34.78% Xytect 2F, an insecticide (Rainbow Treecare ScientificAdvancements). A viscous white liquid was formed.

Example 32

An amount of the composition of Example 30 (1.25%) was mixed with 0.25%Xytect 2F, an insecticide (Rainbow Treecare Scientific Advancements) and98.5% water. A hazy, uniform solution was formed.

Exemplary embodiments described herein may provide one or more of thefollowing benefits: the delivery of polyacrylamide, a proven depositionaid or drift control agent, in a form that is stable for long periods oftime; a polyacrylamide that mixes well in most tanks with EO/PO blockcopolymer for enhanced wetting properties of the composition; thecomposition that may be deliverable in one bottle; dispersability inwater, including embodiments in which the maximum viscosity is notgreater than 1000 cps; low aggregation; high stability and hence longshelf-life; enhanced handling characteristics; enhanced water-carryingproperties; ability to treat soils, including water-repellant soils;superior wetting properties, particularly with EO/PO block copolymerpresent; and others described herein and determinable through practiceof the exemplary embodiments.

The present invention as described herein, taken as a whole with theabstract, specification, and claims, provides sufficient information fora person of ordinary skill in the art to practice the inventiondisclosed and claimed herein. Any measures necessary to practice thepresent invention are well within the skill of a person having ordinaryskill in the art after that person has made a careful study of thepresent disclosure.

Because of this disclosure and solely because of this disclosure,modification of these compositions and methods may become clearer to aperson of ordinary skill in the art. Such modifications are clearlycovered by the present disclosure.

It should be noted that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications may be madewithout departing from the spirit and scope of the present invention andwithout diminishing its attendant advantages.

What is claimed is:
 1. A water-in-oil microemulsion, comprising: apolyacrylamide; a fatty acid comprising a tall oil fatty acid, oleicacid, or a combination of a tall oil fatty acid and oleic acid; asurfactant; an oil continuous phase; and an aqueous discontinuous phasein the oil continuous phase, wherein the water-in-oil microemulsioncontains 6 to 48 parts by weight of the polyacrylamide, 30 to 62 partsby weight of the fatty acid, and 20 to 44 parts by weight of thesurfactant per 100 parts by weight of the polyacrylamide, the fattyacid, and the surfactant combined.
 2. The water-in-oil microemulsion ofclaim 1, wherein the fatty acid comprises the tall oil fatty acid, andwherein the water-in-oil microemulsion contains 6 to 40 parts by weightof the polyacrylamide, 30 to 62 parts by weight of the tall oil fattyacid, and 20 to 44 parts by weight of the surfactant per 100 parts byweight of the polyacrylamide, the tall oil fatty acid, and thesurfactant combined.
 3. The water-in-oil microemulsion of claim 1,wherein the fatty acid comprises the tall oil fatty acid, and whereinthe water-in-oil microemulsion contains 8 to 32 parts by weight of thepolyacrylamide, 30 to 60 parts by weight of the tall oil fatty acid, and24 to 43 parts by weight of the surfactant per 100 parts by weight ofthe polyacrylamide, the tall oil fatty acid, and the surfactantcombined.
 4. The water-in-oil microemulsion of claim 1, wherein thefatty acid comprises the oleic acid, and wherein the water-in-oilmicroemulsion contains 10 to 48 parts by weight of the polyacrylamide,30 to 60 parts by weight of the oleic acid, and 20 to 39 parts by weightof the surfactant per 100 parts by weight of the polyacrylamide, theoleic acid, and the surfactant combined.
 5. The water-in-oilmicroemulsion of claim 1, wherein the fatty acid comprises the oleicacid, and wherein the water-in-oil microemulsion contains 16 to 32 partsby weight of the polyacrylamide, 30 to 60 parts by weight of the oleicacid, and 24 to 38 parts by weight of the surfactant per 100 parts byweight of the polyacrylamide, the oleic acid, and the surfactantcombined.
 6. The water-in-oil microemulsion of claim 1, wherein thewater-in-oil microemulsion is homogenously dispersible in water orwater-based mixtures to form a diluted product substantially completelyfree of solid agglomerates of the polyacrylamide.
 7. The water-in-oilmicroemulsion of claim 1, further comprising an ethylene oxide/propyleneoxide (EO/PO) block copolymer.
 8. The water-in-oil microemulsion ofclaim 1, wherein the surfactant is nonionic and has ahydrophilic-lipophilic balance of greater than 9.3.
 9. The water-in-oilmicroemulsion of claim 1, wherein the surfactant comprises anethoxylate.
 10. The water-in-oil microemulsion of claim 9, wherein theethoxylate comprises nonylphenol ethoxylate, an alcohol ethoxylate, afatty acid ethoxylate, and combinations thereof.
 11. The water-in-oilmicroemulsion of claim 1, wherein the polyacrylamide comprises acombination of a polyacrylamide homopolymer and a polyacrylamidecopolymer.
 12. The water-in-oil microemulsion of claim 1, wherein thepolyacrylamide comprises an anionic polyacrylamide derived fromacrylamide and sodium acrylate.
 13. The water-in-oil microemulsion ofclaim 1, wherein the water-in-oil microemulsion has a total weight, andwherein the polyacrylamide constitutes up to about 15 percent by weightof the total weight.
 14. The water-in-oil microemulsion of claim 1,wherein: the water-in-oil microemulsion has a total weight; thepolyacrylamide constitutes up to about 15 percent by weight of the totalweight; the fatty acid constitutes about 2 percent to about 5 percent byweight of the total weight; and the surfactant comprises a nonionicsurfactant constituting about 9 to about 20 percent by weight of thetotal weight.
 15. The water-in-oil microemulsion of claim 1, wherein theoil constitutes about 10 percent to about 55 percent by weight of atotal weight of the water-in-oil microemulsion, and wherein the oilcomprises cottonseed oil, canola oil, soybean oil, corn oil, palm kerneloil, coconut oil, the methyl ester thereof, the ethyl ester thereof, ora combination thereof.
 16. The water-in-oil microemulsion of claim 1,wherein the oil comprises a paraffinic oil, a naturally occurring oil, aderivative of naturally occurring oils, or a combination thereof. 17.The water-in-oil microemulsion of claim 1, wherein the water-in-oilmicroemulsion is mixable with an aqueous medium to provide a dispersedsolution with a range of 10 to 50 weight percent water, and wherein thedispersed solution has a maximum viscosity of not greater than 1000 cpsin the range.
 18. The water-in-oil microemulsion of claim 1, wherein thewater-in-oil microemulsion is made by combining a nanoemulsion of apolyacrylamide homopolymer, a polyacrylamide copolymer, a polyacrylamideterpolymer, or a combination of two or more of the polyacrylamidehomopolymer, the polyacrylamide copolymer, and the polyacrylamideterpolymer with at least one of the oil, the fatty acid, and thesurfactant.
 19. A method of dispersing a water-in-oil microemulsion intoan aqueous media and applying the composition in an agriculturalapplication, comprising: dispersing a water-in-oil microemulsion in anaqueous medium, the water-in-oil microemulsion comprising apolyacrylamide; a fatty acid comprising a tall oil fatty acid, oleicacid, or a combination of a tall oil fatty acid and oleic acid; asurfactant; an oil continuous phase; and an aqueous discontinuous phasein the oil continuous phase, wherein the water-in-oil microemulsioncontains 6 to 48 parts by weight of the polyacrylamide, 30 to 62 partsby weight of the fatty acid, and 20 to 44 parts by weight of thesurfactant per 100 parts by weight of the polyacrylamide, the fattyacid, and the surfactant combined; allowing micelles of the water-in-oilmicroemulsion to burst in the aqueous medium; and applying the aqueousmedium with the water-in-oil microemulsion dispersed therein to at leastone seed, at least one growing crop, at least one forest area, at leastone turf or other vegetation, at least one soil, at least one crop, or acombination thereof.
 20. A method of dispersing a water-in-oilmicroemulsion into an aqueous medium and applying the water-in-oildispersed in the aqueous medium, comprising: dispersing a water-in-oilmicroemulsion in an aqueous medium, the water-in-oil microemulsioncomprising a polyacrylamide; a fatty acid comprising a tall oil fattyacid, oleic acid, or a combination of a tall oil fatty acid and oleicacid; a surfactant; an oil continuous phase; and an aqueousdiscontinuous phase in the oil continuous phase, wherein thewater-in-oil microemulsion contains 6 to 48 parts by weight of thepolyacrylamide, 30 to 62 parts by weight of the fatty acid, and 20 to 44parts by weight of the surfactant per 100 parts by weight of thepolyacrylamide, the fatty acid, and the surfactant combined; allowingmicelles of the water-in-oil microemulsion to burst in the aqueousmedium; and applying the aqueous medium with the water-in-oilmicroemulsion dispersed therein to at least patch of bare ground, atleast one roadside, at least one industrial area, at least oneright-of-way, at least one water management area, at least one waterway,or a combination thereof.